In a production process of a circuit board, after conductive patterns are formed on the circuit board, it is necessary to inspect that no defect, such as breakage and short-circuit, is included in the formed conductive patterns.
As one technique for inspecting conductive patterns, there has heretofore been known a contact-type inspection technique for performing a conduction test and others of conductive patterns, in such a manner that an electrical signal is supplied from one of probes or pins which are, respectively, in contact with both ends of each of the conductive patterns, and the electrical signal is picked up from the other pin. In this technique, the electrical signal is supplied by putting the pins or metal probes, respectively, on all of the contact terminals of the conductive patterns, and sending an electric current from the metal probes to the conductive patterns.
Late years, in connection with the high densification of conductive patterns, the wiring pitch in the contact terminal region of the conductive patterns has become more accurate and smaller, and a circuit board with a wiring pitch of less than 50 μm has come onto the market. While a probe card having a number of narrow-pitch probes can be prepared for inspecting such a circuit board, it involves a problem of high production cost.
In addition, if a circuit board to be inspected, or object, is variously changed in wiring patterns, a dedicated probe card has to be prepared for each of objects having different wiring patterns. The resultingly increased production cost has hindered the progress of cost reduction of electronic components.
Furthermore, in actual use, the probe card has to be essentially handled to avoid the risk of breakage possibly caused by brittleness or fragility due to its fine structure.